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Home >> Volvo >> 2012 >> XC90 R-Design, FWD >> Repair and Diagnosis (Single Page) >> Steering >> Steering Column >> Electrical Components - Design And Function >> Transmission Control Module (TCM) (4T65 AWD; 2003-2006) >> Function >> Emergency Mode In The Event Of A Fault
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Emergency Mode In The Event Of A Fault

If the transmission control module (TCM) detects a permanent fault, an emergency mode is activated. The transmission control module (TCM) then implements corrective action to protect the transmission, while leaving the car in the best possible drivable condition. Minor malfunctions do not activate an emergency program. There are different programs depending on the type of fault:

Emergency mode is activated for minor faults and the Limp home mode for the most serious faults. If the malfunction is intermittent, the transmission control module (TCM) returns to normal operation the next time the ignition is switched on.

Emergency mode 

A text message is displayed in the combined instrument panel for diagnostic trouble codes (DTCs) stored in the transmission control module (TCM).

The transmission shifts in all gears but transmits no signal to the lock-up solenoid. This means that lock-up is not available.

Limp home mode 

A text message is displayed in the combined instrument panel for diagnostic trouble codes (DTCs) stored in the transmission control module (TCM).

The transmission control module (TCM) interrupts the activation of all solenoids. This means that no shifting is possible. The transmission only functions in 3rd gear and back-up (reverse) gear.

No regulation of line pressure solenoid STH. Maximum system pressure constantly which results in harsh meshing and harsher shifts when engaging P-R, N-R and N-D. This can also result in a whining noise from the transmission pump.